This invention relates to a heat softening thermally conductive (HSTC) composition and methods for preparation and use of the same. More particularly, this invention relates to a HSTC composition comprising a silicone resin system and a thermally conductive filler. The HSTC composition can be used as a thermal interface material (TIM).
Electronic components such as semiconductors, transistors, integrated circuits (ICs), discrete devices, and others known in the art are designed to operate at a normal operating temperature or within a normal operating temperature range. However, the operation of an electronic component generates heat. If sufficient heat is not removed, the electronic component will operate at a temperature significantly above its normal operating temperature. Excessive temperatures can adversely affect performance of the electronic component and operation of the device associated therewith and negatively impact mean time between failures.
To avoid these problems, heat can be removed by thermal conduction from the electronic component to a heat sink. The heat sink can then be cooled by any convenient means such as convection or radiation techniques. During thermal conduction, heat can be transferred from the electronic component to the heat sink by surface contact between the electronic component and the heat sink or by contact of the electronic component and heat sink with a TIM.
Surfaces of the electronic component and the heat sink are typically not completely smooth, therefore, it is difficult to achieve full contact between the surfaces. Air spaces, which are poor thermal conductors, appear between the surfaces and increase impedance. These spaces can be filled by inserting a TIM between the surfaces. The lower the thermal resistance of the TIM, the greater the flow of heat from the electronic component to the heat sink.
Some commercially available TIMs are elastomers filled with thermally conductive fillers. However, elastomers suffer from the drawbacks that a high pressure is required to reduce the thermal interfacial contact resistance and promote effective heat transfer between the substrate and the TIM.
Silicone greases with conductive fillers have also been proposed as TIMs. However, greases suffer from the drawbacks that they can be messy to apply and can flow out of the spaces after application.
HSTC compositions are advantageous in solving the above problems because they can be handled as a solid at low temperatures and soften at an elevated temperature. The softening temperature can be equal to or above the normal operating temperature of the electronic component.
HSTC compositions can comprise organic materials such as waxes, and conductive fillers. However, organic waxes suffer from the drawback that they can flow out of the spaces after application, during operation of the electronic component. Organic waxes may also be brittle at room temperature.
This invention relates to a heat softening thermally conductive (HSTC) composition and methods for its preparation and use. The HSTC composition comprises a matrix and a thermally conductive filler. The matrix comprises a silicone resin.